1. Field of the Invention
The present invention relates to a snowmobile, and more particularly to an arrangement of components within a snowmobile, in which the layout of selected accessory devices for an internal combustion engine mounted on the snowmobile is improved.
2. Description of the Background Art
There are some examples of known snowmobiles in which the snowmobile has an internal combustion engine with compactly arranged accessory devices, to accommodate limited available interior space in the snowmobile body. These arrangement considerations are especially relevant in a small-sized snowmobile. An example of a small snowmobile having such a structure is disclosed in Japanese Laid-Open Patent No. 2002-266653 (pp. 4–5, FIG. 2), in which an internal combustion engine is installed within a limited space in the vehicle body to ensure an advantage in the mounting space. The snowmobile disclosed in Japanese Laid-Open Patent No. 2002-266653 has a shaft layout structure such that a crankshaft, as well as a traveling power output shaft and a pump drive shaft (auxiliary device shaft), are arranged parallel with one another in the vehicular transverse direction. As such, the shafts form a triangular shape when viewed from the side of the vehicle body. To achieve this configuration, the pump drive shaft is disposed below the power output shaft, and the crankshaft is disposed at an intermediate position between the power output shaft and the pump drive shaft, and on a rear side of the engine. According to this shaft layout structure, accessory devices to be arranged around the internal combustion engine are arranged compactly on both front and rear sides of the engine.
According to a snowmobile 060 of the invention disclosed in Japanese Laid-Open Patent No. 2002-266653, which is illustrated in FIGS. 13 and 14 of the present drawings for comparative purposes, there is used a power output shaft 02. The power output shaft 02 is connected through the engagement of gears to a crankshaft 01 of an internal combustion engine 0E mounted on the snowmobile 060, and rotation of the power output shaft 02 is transmitted to an endless track belt 065 through a V belt type automatic transmission 066, whereby the snowmobile is driven for travel.
In the internal combustion engine OE mounted on the snowmobile 060 of this prior art reference, the crankshaft 01, the power output shaft 02 for driving the snowmobile 060, and a pump drive shaft 03 as an auxiliary device shaft, are arranged so as to be parallel with one another in the transverse direction of the snowmobile 060 and so as to mutually form a triangle when viewed from the side of the vehicle body.
More particularly, a pump drive shaft 03, for activating a cooling pump and an oil pump, is disposed below the power output shaft 02. The crankshaft 01 is disposed at an intermediate position between and behind the power output shaft 02 and the pump drive shaft 03. As a result, various accessory devices to be arranged around the engine OE are disposed compactly, especially on both front and rear sides of the engine OE.
The compact layout structure of various accessory devices around the engine OE in the invention disclosed in Japanese Laid-Open Patent No. 2002-266653 leads to a reduction in size of the internal combustion engine OE. Such a small-sized internal combustion engine OE in the small-sized snowmobile 060 not only facilitates the installation thereof, but also provides an advantageous structure in point of space.
Thus, Japanese Laid-Open Patent No. 2002-266653 provides an improved structure for effective use of such an extremely limited body space as in the small-sized snowmobile, as compared to older art which preceded publication of this reference. However, the provision of a further improved structure for effective use of body space in the snowmobile, and for facilitating installation of an internal combustion engine onto the snowmobile body is needed. Particularly, an improved structure is needed for a small-sized snowmobile for effective use of mounting space for an internal combustion engine, and various accessory devices associated with the engine, which occupy a large relative importance related to the available space.